Nonalcoholic Fatty Liver Disease (NAFLD) is an increasingly recognized form of chronic liver disease affecting both adults and children that may progress to cirrhosis and its feared complications of portal hypertension, liver failure and hepatocellular carcinoma. NAFLD represents a spectrum of conditions ranging form simple accumulation of fat in the liver (steatosis), to steatosis plus hepatocellular injury (steatohepatitis or NASH), to advanced fibrosis and cirrhosis. Simple steatosis is thought to follow a benign non-progressive course, while NASH may lead to cirrhosis in up to 25% of patients. The pathogenesis of NAFLD as it relates to tissue injury and disease progression remains incompletely understood and there is currently no proven effective medication to stop the progression of this disease. At present time, a liver biopsy is the only reliable means to assess the disease severity in NAFLD.